Symptomatic kidney stones are a significant source of pain and morbidity, affect up to 12% of Americans and generate more than $2 billion in annual healthcare costs. With incidence rates rising, a silent, under-recognized danger for patients with kidney stones is their repetitive exposure to ionizing radiation. Consequently, strategies to reduce patient exposure to ionizing radiation may be of both short and long-term benefit to patients with urinary stone disease. In this study, we propose to validate contrast enhanced ultrasound (CEUS) nephrostogram to replace fluoroscopic nephrostogram for evaluating antegrade renal drainage. Our results will demonstrate that utilizing CEUS in this setting can lead to significantly decreased patient radiation exposure, laying the groundwork to introduce a completely new way of imaging the kidney and ureter. Ultrasound is a powerful, portable imaging modality free of the dangers of ionizing radiation, currently in use across many diagnostic settings. The addition of intravenously injected microbubble contrast agents has extended the applicability of ultrasound to new imaging applications that used to rely on computed tomography (CT) or fluoroscopy. CEUS facilitates dynamic real-time assessment of visceral organs with excellent spatial resolution and is less likely to cause contrast-related allergic reactions compared to CT or fluoroscopy. This pilot study will be the first to evaluate th feasibility of CEUS for detection of ureteral patency and antegrade renal drainage as a replacement to fluoroscopic nephrostogram. Our preliminary work demonstrates that using ultrasound during percutaneous renal stone surgery rapidle reduces patient exposure to ionizing radiation. In addition, our initial experience of contrast enhanced ultrasound nephrostogram demonstrates it to be a viable alternative to fluoroscopic nephrostogram. Given these findings, we hypothesize that contrast enhanced ultrasound nephrostogram will be non-inferior to fluoroscopic nephrostogram to evaluate ureteral patency in patients with nephrostomy tubes after percutaneous renal stone surgery. The aims of the proposed study are: (1) Optimize the parameters for contrast enhanced ultrasound nephrostogram imaging for patients with nephrostomy tubes, and (2) Perform a prospective pilot cohort study comparing contrast enhanced ultrasound nephrostogram to fluoroscopic nephrostogram to identify unobstructed antegrade renal drainage. The significance of developing contrast enhanced ultrasound nephrostogram as an alternative imaging modality to traditional fluoroscopic nephrostogram is that patients with nephrostomy tubes in place will be exposed to drastically reduced levels of ionizing radiation exposure. The innovation of this project is the development of a new application for contrast enhanced ultrasound, one that imparts minimal risk to the patient, can be used in many settings, and can be easily adopted. We believe that in the future, contrast enhanced ultrasound with nephrostomy injection will be a routine component of ultrasound and currently represents a transformative advance in renal imaging.